National Transportation Safety Board investigator Michael Folkerts said at a news conference on Tuesday the twin-engine Beechcraft BE58 plane was last spotted on air traffic control equipment about 200 feet above the rocky terrain of the Texas Hill Country. He added the airplane hit the ground “upright” about six miles from the Kerrville Municipal Airport.

Folkerts said the plane crashed while moving at a high vertical, but low horizontal speed that is inconsistent with an attempted landing. He said the group was flying to Kerrville on business.

The initial investigation by the NTSB will focus on mechanics. Folkerts said they will check the aircraft’s systems, including the engines, propellers and the fuel system.

“We do have engine data that we are going to be able to download, that should give us some insight as to what may have been going on with the engines,” he noted.

The six victims of the deadly crash were all Houston residents. Jeffrey C. Weiss, 65, was a senior vice president for investments at Raymond James and Associates in Houston. The Texas Department of Public Safety said Weiss, who co-owned the plane, was at the controls when the aircraft went down just before 9 a.m. Monday while approaching Kerrville.

Investigators will also look into the pilot’s health. The NTSB says Weiss was an experienced pilot who was certified to fly airline transport planes and who had more than 5,000 flight hours. The plane’s co-owners say Weiss regularly volunteered to fly sick people from around the country to hospitals in Dallas and Houston.

More information is expected next week but the investigation could take a year to be completed.